something wrong here
Friends
This is a simple question. 109kts against the wind, 129 knots with the wind therefore 119ktas still air. Drift is not relevant because the reverse is flown not the reciprocal i.e. the paper pilot flies back to the start point. I can't quite see why we need to know Mach No but under ISA conditions at 7000ft the temp should be 1 deg C but we are told "today" it is 15 deg C. That makes local speed of sound 1118.64ft/sec so M0.18 it is. Now using an electronic calculator rather than the whirly wheel I obtain CAS of 105kts. Thus agreeing with old Smokey. So the IAS under-reads by 5kts. So either a) the examiner got it wrong or b) we are supposed to second guess what the examiner wants or c) we have not been given the question in full. If on the other hand we had to give evidence of our working some credit could be gained and the exam would be a continuation of the learning process.